Introduction to Peripheral Nervous System/Thoracic Wall Anatomy Flashcards
What makes up the central nervous system?
- brain
- spinal cord
What makes up the peripheral nervous system?
- 12 pairs of cranial nerves
- 31 pairs of spinal nerves
The 12 pairs of cranial nerves in the PNS arise from what?
the brain or brainstem
The 31 pairs of spinal nerves in the PNS arise from what?
the spinal cord
Neurons that receive information from our sensory organs (eye, skin) and transmit this input to the CNS are called what?
afferent neurons
Neurons that send impulses from the CNS to limbs and organs are called what?
efferent neurons
What transmits information within the CNS (both sensory and motor neurons)?
interneurons
Most of the neurons in the body are what?
interneurons
Pain, touch, and pressure is associated with what type of neurons?
sensory/afferent neurons
What carries information away from the cell body in the CNS to muscles and glands?
motor/efferent neurons
In the spinal cord, where can you find the dorsal root ganglion?
out in the periphery, not in the cord
What are the two types of afferent/sensory stimuli?
- soma (somatic sensory)
- viscera (visceral sensory)
Where is somatic sensory from?
skin, joints, skeletal mm, special senses (outside world)
Where is visceral sensory from?
the viscera (internal organs such as heart, lungs, stomach, and bladder)
What are the two types of effector motors?
- voluntary (skeletal muscles)
- involuntary (ANS-regulated internal body functions)
General visceral efferent nerves are always associated with what?
the ANS
What consists of sensory and motor fibers to/from the skin, skeletal muscle, and joints?
somatic nervous system
What consists of sensory and motor fibers to all smooth muscle, cardiac muscle, and glands?
autonomic nervous system
What consists of the plexuses and ganglia of the GI tract that regulate bowel secretion, absorption, and motility (originally considered part of ANS); they are linked to the ANS for optimal regulation?
enteric nervous system
What is a one-neuron motor system?
somatic nervous system
Where can you find the motor/efferent neurons in the somatic nervous system?
in the CNS, and an axon projects to the peripheral target (such as skeletal muscle)
Where can you find the sensory/afferent neurons in the somatic nervous system?
in the peripheral ganglion (spinal ganglion) and conveys sensory info from the skin, muscle or joint to the CNS
What is the unilateral area of skin innervated by the somatic sensory fibers from a single spinal cord level called?
dermatome
What is a two-neuron motor system?
autonomic nervous system
Where can you find the neurons associated with the ANS?
first neuron will reside in the CNS and the second neuron will reside in the peripheral autonomic ganglion
What is the axon of the first neuron of the ANS termed?
preganglionic
What is the axon of the second neuron of the ANS termed?
postganglionic
What are the two divisions of the ANS?
- sympathetic
- parasympathetic
What consists of ganglia and nerve plexuses in the wall and mesenteries of the GI tract?
enteric nervous system
What are the names of the ganglia and their neural networks named in the enteric nervous system?
- Myenteric (Auerbach’s) plexuses
- submucosal (Meissner’s) plexuses
Which enteric plexus has the ganglia and nerves located between the circular and longitudinal smooth muscle layers of the muscularis externa of the bowel wall?
myenteric (Auerbach’s) plexuses
Which enteric plexus has ganglia and nerves located in the submucosa of the bowel wall?
submucosal (Meissner’s) plexus
The vagus nerve is associated with what division of the autonomic nervous system?
parasympathetic division
What carries sensory info from receptors in the skin/other organs to the CNS?
afferent neurons
The cell bodies of which neurons are located outside of the spinal cord?
afferent neurons
What carries motor info from the brain to the PNS?
efferent neurons
The cell bodies of what neurons are located in the ventral horn of the spinal cord?
efferent neurons
What fibers travel to the surface of the body and limbs that are sensitive to touch, temperature, and noxious stimuli?
general somatic afferent fibers
What fibers are associated with vision, hearing, and balance?
special sensory afferent (SSA) fibers
What fibers are usually pain or reflex sensations from the internal organs, glands, and blood vessels to the CNS?
general visceral afferent fibers
What fibers are voluntary motor fibers?
general somatic efferent fibers
What fibers are found in the cardia, smooth muscle, glands and are involuntary?
general visceral efferent fibers
What fibers are found in the muscles of the pharyngeal arches?
special visceral efferent (SVE)
General somatosensory (GSA) fibers have nerve impulses that travel from what to what?
periphery to the CNS
General somatosensory (GSA) neurons have how many neurons and where is the location of the cell body?
- 1 neuron
- dorsal root ganglion
General somatosensory (GSA) neurons have what functional modality?
somato sensory
What spinal cord level nerve provides fibers to the nipple?
T4 (or T5)
What spinal cord level nerve provides fibers to the xiphoid process?
T7 (or T6)
What spinal cord level nerve provides fibers to the umbilicus?
T10
What spinal cord level nerve provides fibers to the flex line of the thigh on the trunk/groin?
L1
What spinal cord level nerve provide fibers to the perineum?
S2
All spinal nerves receive sensory input from a specific skin area except for what spinal nerve?
C1
Injury/severe/anesthetize of 3-consecutive spinal nerves will produce what?
a complete sensory loss in 1 dermatome
Trunk dermatomes have extensive what?
overlap
What is the clinical significance of dermatomes?
- assessing spinal cord level injuries
- diagnosing peripheral nerve injuries (herniated IVD)
- “referred pain” (visceral pain referred to soma)
- origin of viral infection (herpes zoster - shingles)
Somatomotor (GSE) neurons have nerve impulses that travel from what to what?
CNS to the periphery
Somatomotor (GSE) fibers have how many neurons and where are their cell bodies located?
- 1
- ventral horn
Somatomotor (GSE) neurons have what type of functional modality?
skeletal muscle only
Internal organs in the ANS have what type of fibers?
visceral efferent fibers
How many cranial nerves have parasympathetic fibers?
4 (III, VII, IX, X)
How many sacral nerves have parasympathetic fibers?
3 (S2, S3, S4)
Parasympathetic fibers in the sacral region run to what organs?
- large intestine
- bladder
- reproductive organs
What is the only cranial nerve with parasympathetic fibers that runs to the head and neck region?
vagus n
Where is the celiac plexus near?
the artery branches
The parasympathetic nervous system is made up of what region?
craniosacral region
The sympathetic nervous system is made up of what region?
thoracolumbar region
What does the thoracolumbar region span from?
T1-L2
Sympathetic fibers in the thoracolumbar region travel to what?
- body wall (arrector pili and blood vessel smooth muscle, sweat glands)
- internal organs
What fibers travel to the body wall: parasympathetic, sympathetic, or both?
sympathetic ONLY
What fibers travel to internal organs: parasympathetic, sympathetic, or both?
both
What type of pain is generally diffuse/poorly localized?
visceral pain
What is the theory that the convergence of nociceptive neurons in the spinal dorsal root from multiple sources and has higher centers in the brain unable to identify actual input source and “defaults” to the more common source of pain?
Central convergence theory of referred pain
What are the 3 layers of the intercostal muscles?
- external intercostal m
- internal intercostal m
- innermost intercostal m
What are the minor thoracic muscles?
- transverse thoracic m
- subcostal m
- levator castorum m
- serratus posterior mm (superior and inferior)
What muscles attach to the ribs and pectoral girdle?
upper limb muscles
The thoracic segments of the spinal cord supply how many pairs of thoracic spinal nerves to the thoracic wall?
12 pairs
As thoracic spinal nerves leave the IV foramina, they divide into what?
anterior and posterior rami
What forms the intercostal nerves that run along the extent of the intercostal spaces?
the anterior rami of T1-T11
What forms the subcostal nerves?
the anterior rami of T12 nerves, inferior to the 12th rib
What passes posteriorly immediately lateral to the articular processes of the vertebrae to supply the bones, joints, deep back muscles, and skin of the back in the thoracic region?
the posterior rami of the thoracic spinal nerves
Sweat glands and the body wall are only supplied by what?
sympathetic fibers
The arteries of the thoracic wall are derived from?
- thoracic aorta (through posterior intercostal and subcostal aa)
- subclavian artery (through internal thoracic and supreme intercostal aa)
- axillary artery (through superior and lateral thoracic aa)
Each intercostal space is supplied by what three arteries?
- posterior intercostal artery
- collateral branch of the posterior intercostal artery
- anterior intercostal artery
What accompanies the intercostal arteries and nerves and lie most superior in the costal grooves?
veins of the thoracic wall
How many posterior intercostal veins are there in the thoracic wall?
11
How many subcostal veins are there in the thoracic wall?
one on each side
What do the posterior intercostal veins anastomose with?
anterior intercostal veins, tributaries of the internal thoracic veins
Most posterior intercostal veins end where?
in the azygos/hemi-azygos venous system, which conveys venous blood to the superior vena cava